"After three months, both Lee and Twitter came to the conclusion that the match was not perfect," Twitter co-founder Biz Stone told SAI via email. "We are seeking to fill this role with a refined search criteria that fits with our plan to scale Twitter as a company and as a service."

What's going on at Twitter? More than one thing, from what we can gather. While Blaine has taken a lot of heat in certain corners of the blogosphere for Twitter's scaling/downtime issues, people familiar with the company say his departure from the company was indeed amicable, and that he hasn't been held directly responsible for the service's stumbles and lurches.

But when Lee came on board January 8, the company described him as a "perfect match" who had "demonstrated experience creating sophisticated back-end software along
with his genuine enthusiasm for building global systems that operate at
scale."

We won't opine about the technical challenges that Twitter is facing, because we don't understand them -- we're happy when we can make our DVR work. But we do understand that the company is preparing to raise a Series C round, after raising some $5 million at a $20 million valuation last summer. If Twitter wants more money and a higher value, it's going to have to convince investors it has its tech talent issues solved.

UPDATE: We hear Twitter is trying to raise $15 million, at a $60 million valuation.